1. Field of the Invention
The invention relates to abrasion machining of friable material such as carbon of the type used to make electro erosion machining electrodes or the like and refers more specifically to cutting masters for abrasion machining electrodes for electro erosion machining from carbon or the like which cutting masters have an abrasive mirror image surface of the electrode to be machined that differs in size from the electrode to be machined by a predetermined amount and the method of making such cutting masters.
2. Description of the Prior Art
Other than the disclosure of the above referenced related patent applications and the references cited therein, there is no known prior art in the field of precision total form abrasion machining. Abrasion machining has been accomplished in the past by relatively uncontrolled grinding, chipping, etching, engraving, and the like, which does not produce total form machining and is for the most part substantially non-precision. Thus, sculpturing with a chisel may be considered abrasion machining but has a precision controllable only by the artist in his manual handling of tools. Even with accomplished artists, sculpturing is not total form machining, but is single point or line machining at best. Similarly, mechanical etching and engraving has been controlled only by the skill of the hands of the etcher and is single point machining in nature. Grinding, while it may be precision, is certainly not total form machining of the type considered in the present application and in the above referenced applications, and at best is only single line and not total form machining. Thus, in grinding there is a single line of contact between the workpiece and the grinding wheel rather than a point contact as with an etching or engraving needle or chisel, or substantially total contact between an abrasive surface of a cutting master and a workpiece as in total form abrasion machining.